netdev - [PATCH v1 net 02/15] ipv4: Fix data-races around sysctl_fib_multipath_hash

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Date:   Mon, 18 Jul 2022 10:26:40 -0700
From:   Kuniyuki Iwashima <kuniyu@...zon.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        David Ahern <dsahern@...nel.org>
CC:     Kuniyuki Iwashima <kuniyu@...zon.com>,
        Kuniyuki Iwashima <kuni1840@...il.com>,
        <netdev@...r.kernel.org>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Subject: [PATCH v1 net 02/15] ipv4: Fix data-races around sysctl_fib_multipath_hash_policy.

While reading sysctl_fib_multipath_hash_policy, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its readers.

Fixes: bf4e0a3db97e ("net: ipv4: add support for ECMP hash policy choice")
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
CC: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 2 +-
 net/ipv4/route.c                                      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 868d28f3b4e1..de63a5f3b767 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -10324,7 +10324,7 @@ static void mlxsw_sp_mp4_hash_init(struct mlxsw_sp *mlxsw_sp,
 	unsigned long *fields = config->fields;
 	u32 hash_fields;
 
-	switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
+	switch (READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_policy)) {
 	case 0:
 		mlxsw_sp_mp4_hash_outer_addr(config);
 		break;
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 91c4f60de75a..521194dd1c99 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -2048,7 +2048,7 @@ int fib_multipath_hash(const struct net *net, const struct flowi4 *fl4,
 	struct flow_keys hash_keys;
 	u32 mhash = 0;
 
-	switch (net->ipv4.sysctl_fib_multipath_hash_policy) {
+	switch (READ_ONCE(net->ipv4.sysctl_fib_multipath_hash_policy)) {
 	case 0:
 		memset(&hash_keys, 0, sizeof(hash_keys));
 		hash_keys.control.addr_type = FLOW_DISSECTOR_KEY_IPV4_ADDRS;
-- 
2.30.2